Abstract

Hendra virus (HeV) causes highly lethal disease in horses and humans in the eastern Australian states of Queensland (QLD) and New South Wales (NSW), with multiple equine cases now reported on an annual basis. Infection and excretion dynamics in pteropid bats (flying-foxes), the recognised natural reservoir, are incompletely understood. We sought to identify key spatial and temporal factors associated with excretion in flying-foxes over a 2300 km latitudinal gradient from northern QLD to southern NSW which encompassed all known equine case locations. The aim was to strengthen knowledge of Hendra virus ecology in flying-foxes to improve spillover risk prediction and exposure risk mitigation strategies, and thus better protect horses and humans. Monthly pooled urine samples were collected from under roosting flying-foxes over a three-year period and screened for HeV RNA by quantitative RT-PCR. A generalised linear model was employed to investigate spatiotemporal associations with HeV detection in 13,968 samples from 27 roosts. There was a non-linear relationship between mean HeV excretion prevalence and five latitudinal regions, with excretion moderate in northern and central QLD, highest in southern QLD/northern NSW, moderate in central NSW, and negligible in southern NSW. Highest HeV positivity occurred where black or spectacled flying-foxes were present; nil or very low positivity rates occurred in exclusive grey-headed flying-fox roosts. Similarly, little red flying-foxes are evidently not a significant source of virus, as their periodic extreme increase in numbers at some roosts was not associated with any concurrent increase in HeV detection. There was a consistent, strong winter seasonality to excretion in the southern QLD/northern NSW and central NSW regions. This new information allows risk management strategies to be refined and targeted, mindful of the potential for spatial risk profiles to shift over time with changes in flying-fox species distribution.

Field, Hume Jordan, David Edson, Daniel Morris, Stephen Melville, Debra Parry-Jones, Kerryn Broos, Alice Divljan, Anja McMichael, Lee Davis, Rodney Kung, Nina Kirkland, Peter Smith, Craig
State of Queensland; State of New South Wales; Commonwealth of Australia under the National Hendra Virus Research Program; Queensland Department of Agriculture and Fisheries; NSW Department of Primary Industries
This research was funded by the State of Queensland (http://www.qld.gov.au), the State of New South Wales (https://www.nsw.gov.au) and the Commonwealth of Australia (http://www.australia.gov.au) under the National Hendra Virus Research Program. HF was core-funded by the Queensland Department of Agriculture and Fisheries; PK and DJ were core-funded by the NSW Department of Primary Industries. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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PUBLIC LIBRARY SCIENCE
SAN FRANCISCO
PLOS ONE